Chemical analysis of liquids under vacuum,especially at surface regions and at liquid interfaces, can yield valuable data and information that might provide insight into environmental and biological systems. However, many of the instruments for analysis of surfaces and interfaces are vacuum based, and are not compatible with the high vapor pressure associated with liquid-phase samples. While some approaches exist for investigating liquids, many involve jets that put a large (sometimes overwhelming) load on vacuum pumps and/or significant cooling that limits the kinds of available analyses. Accordingly, methods and systems are needed for analyzing liquids under vacuum.